Major research published today has provided compelling backing for claims that dieters weaning themselves off sugar will see their waistlines shrink.

An Otago University-led study into the effects of sugar, published in the British Medical Journal, found cutting down on the sweetener would see a "small but significant" reduction in body weight.

The study, commissioned by the World Health Organisation, says battling sugary diets should be part of a global strategy to tackle the obesity epidemic.

Researchers examined 8000 trials and 10,000 observational studies published internationally up to December 2011.

They then analysed nearly 70 studies which specifically looked at sugar's effect on body weight.

They found that by cutting down sugar intake over a medium term, an adult could lose 0.8 kilograms.

Increasing sugar intake over the same period could lead to a 0.75kg increase in weight.

The research found that for children the results were less consistent because they were less likely to stick to a strict diet regime, but those who guzzled sugary drinks were much more likely to be overweight.

Dr Lisa Te Morenga, one of the authors of the research, said it made sense to cut back on sugar.

"It seems easier to over-eat if your diet includes lots of sugary foods and drinks," she said.

"When you overeat you gain weight."

Though the perils of sugar have enjoyed a lot of attention in recent years, Te Morenga said this was one of the first studies to offer compelling evidence.

"There have been a lot of claims in the media about the dangers of sugar, but it hasn't really been backed up by a lot of strong research," she said.

One scientific article was released last year by a US pediatrician about the toxic nature of sugar, but it was very theoretical, she said.

"[Other] research was based on very short-term studies in humans who are fed a lot of sugar, or animal studies," said Te Morenga.

"So when you look at really strong, sound evidence showing sugar intakes at levels that people might actually eat, there is not a lot of strong evidence there."

She said the research could be used by the World Health Organisation to shape food policy.